The invention relates to a cutting device for agricultural harvesting machines, for example, loading trailers (pick-up trailers) or baling presses, for harvesting agricultural stalk crop or leaf crop such as grass or hay. The cutting device comprises a conveying channel and a plurality of cutting knives that, arranged in at least one row, are pivotably supported and project into the conveying channel in the cutting position. For comminuting the stalk crop, the cutting knives interact in the conveying channel with a conveying member that is provided with conveying tines and is rotatably driven about a horizontal axis that is oriented transversely to the travel and working direction. The cutting device further comprises adjusting devices that yieldingly support each individual cutting knife in the cutting position. The cutting device further comprises a preselecting device for selecting a group of cutting knives which are pivoted into the cutting position upon activation by a knife switching device.
Such cutting devices are known in practice in numerous configurations and comprises substantially a conveying member, driven in rotation about a horizontal axis and provided with conveying tines, which interacts with cutting knives that are projecting into the conveying channel for cutting the stalk or leaf crop that has been picked up by a pick-up device and for supplying the cut crop to a downstream loading space. In particular in case of baling presses for producing round or square crop bales, only a limited mounting space is available for installation of such cutting devices.
DE 31 41 414 A1 discloses a cutting device for a self-loading trailer in which each knife is supported by a springy and yielding knife lever in the cutting position so that in this way the knife can automatically give way when a stone or another foreign object is encountered. The knife levers are supported approximately with their center on a stationary bolt wherein the lever section which is facing the knife is engaging with a knife roller provided thereat a recess at the back of the knife and the other lever section is engaging a cam disk of the switching shaft downstream of the knife levers. For each knife lever, and thus for each knife, a cam disc is provided wherein the cam discs are arranged displaced relative to each other on the circumference of the switching shaft in such a way that either all of the knife levers, a certain number of the knife levers, or no knife lever is in engagement with a cam disc for adjusting the cutting length of the cutting device. This cutting device is in particular disadvantageous in that for actuation of the switching shaft and thus for adjustment of the cutting length such a great force expenditure is required that a direct manual rotation of the switching shaft by an operator is hardly possible. Instead, complex transmissions or other similar drive means are required.
In DE 32 13 199 C2, a loading trailer with a cutting device is disclosed in which the cutting knives that are projecting into the conveying channel are supported in their cutting position by means of support pawls which are mounted on a switching shaft in individual rows in axis-parallel orientation with different numbers of pawls, respectively. Support edges on the back of the cutting knives are supported with formation of an acute pressure angle on the support pawls of the switching shaft so that, when an excessive load occurs at one or several knives, the support pawls move out of the interaction area at the support edges of the cutting knives by rotation of the switching shaft, counter to the action of an overload protection device, and in this way a pivot movement of the cutting knives out of the cutting position into a non-cutting position is enabled. A disadvantage of this cutting device resides in that, when a stone or a similar foreign object impacts on one cutting knife, simultaneously all activated cutting knives are released to carry out a pivot movement out of the cutting position. A securing action of individual cutting knives against overload and damage is thus not possible.
EP 2 653 025 A1 discloses a further cutting device. It is characterized by a selection mechanism correlated with the tensioning units of the cutting knives; the selection mechanism can activate selected tensioning units from an inactive state, in which they are without engagement with the common adjusting device, into an active state in which they are in engagement with the common adjusting device. The common selection mechanism thus serves to move individual or all of the tensioning units between two states wherein the common adjusting device, depending on the state of the tensioning unit, is in engagement only with selected tensioning units so that only the latter must be moved by the common adjusting device, thus the required force expenditure is reduced. The actuation of the selection mechanism however requires an increased force expenditure due to the weight of the selected tensioning units that are lifted into the active state and due the friction resistances between the cams of the selection mechanism and the spiral springs of the tensioning units. In addition, the wear of the spiral springs at the contact locations with the cam has a negative effect on their service life, which is disadvantageous.
It is the object of the invention to provide an improved cutting device for agricultural harvesting machines of the aforementioned kind which in a compact configuration ensure a reliable securing action of each individual cutting knife, which can be produced inexpensively and simply, and in which an adjustment of the cutting length can be performed by an operator with a force expenditure that is as low as possible.